Add empty check for path in UsageGraph

If path is empty, skip method since there is nothing to draw.

Bug: 132728523
Test: RunSettingsRoboTests
Change-Id: I6fdb7c2f69d3d658c47b58c7304cfeb7d4010a46

src/com/android/settings/widget/UsageGraph.java

@@ -288,7 +288,11 @@ public class UsageGraph extends View {
         canvas.drawPath(mPath, paint);
     }
 
-    private void drawFilledPath(Canvas canvas, SparseIntArray localPaths, Paint paint) {
+    @VisibleForTesting
+    void drawFilledPath(Canvas canvas, SparseIntArray localPaths, Paint paint) {
+        if (localPaths.size() == 0) {
+            return;
+        }
         mPath.reset();
         float lastStartX = localPaths.keyAt(0);
         mPath.moveTo(localPaths.keyAt(0), localPaths.valueAt(0));

tests/robotests/src/com/android/settings/widget/UsageGraphTest.java

@@ -24,6 +24,8 @@ import static org.mockito.Mockito.when;
 
 import android.content.Context;
 import android.content.res.Resources;
+import android.graphics.Canvas;
+import android.graphics.Paint;
 import android.util.SparseIntArray;
 
 import com.android.settingslib.R;
@@ -177,4 +179,14 @@ public class UsageGraphTest {
         assertThat(localPaths.keyAt(5)).isEqualTo(1001);
         assertThat(localPaths.valueAt(5)).isEqualTo(-1);
     }
+
+    @Test
+    public void drawFilledPath_emptyPath_shouldNotCrash() {
+        final Canvas canvas = new Canvas();
+        final SparseIntArray localPaths = new SparseIntArray();
+        final Paint paint = new Paint();
+
+        // Should not crash
+        mGraph.drawFilledPath(canvas, localPaths, paint);
+    }
 }